Well, I've having hissing sound that sounded like I had an exhaust leak. I got around taking some of my plumbings and heat shield. Then I found my problem. On #5, my head gasket was leaking. But I had no coolant pressure built, water in the oil nor oil in my radiator. I've had no mark on the side of the block and the compression test was good. (I guess Ishould have done the leak down.) The gasket must have cracked right in between the oil hole and water jacket. Weird.